unequal, patent branches. Branches flexuous, spreading' to all sides, once, 

 twice, or several times irregularly decomposed, the smaller subdichotomous ; 

 all gradually attenuated upwards and ending in acute points, naked or 

 furnished with minute, lateral, spine-like, patent ramuli. All the axils are 

 rounded. The lesser branches are often secund ; the ramuli sometimes 

 converted into tendi'ils. Cydocarps as large as poppy-seed, rather nume- 

 rous on the upper or under edges of the lesser branches, often secund, 

 containing a compound nucleus {favelUdium) of densely packed spores. 

 Colour a dull brown-red, becoming darker in drying. Substance carti- 

 laginous and fleshy, firm, rather stifl:". In drying the plant shrinks, and very 

 imperfectly adheres to paper. 



A comparison of the lower lialf of Fig. 3 of the present Plate 

 with Pig. 4 of Plate CXLL, will show how close an agreement 

 there is in cellular structure between the frond of Acanthococcics 

 and of this, the typical species of Mi/chodea^ although the struc- 

 ture of the cystocaij) in these genera is so different that they 

 cannot be referred to the same Natural Family, one having pe- 

 dicellate spores laxly springing from a honeycombed placenta, 

 the other having dense manses of spores merely separated by the 

 dead cell-walls within which they were organized. 



The genus Mychodea is almost the same as Cystodonium, with 

 which Kiitzing and Agardh unite it, but differs in having a 

 perfectly ejcternal, instead of an immersed, cystocarp. It there- 

 fore differs from Cysfoclonium nearly as Gigartina differs from 

 Iridaa, and so far as known is confined to the Australian seas, 

 where there are several species. The generic character formerly 

 given in Loud. Journ. Bot. is incorrect, and now amended. 



Fig. 1. Mychodea carnosa, — the natural size. 2. Apex of a small fertile 

 branch, with three conceptacles. 3. Cross section of the frond, and of a con- 

 ceptacle. 4. Spores from the latter: — magnified. 



